U.S. savings bonds: More than 45 million matured savings bonds, worth nearly $16 billion, remain unredeemed, according to the U.S. Department of the Treasury. To search the database, visit treasuryhunt.gov.

Tax refunds: In 2011, the Internal Revenue Service said it had $153.3 million in tax refund checksthat wereundeliverable. To make sure you’ve received your checks, visit the IRS’s Where’s my refund? tool.

Overbid proceeds: If a foreclosed home or tax lien for delinquent taxes is sold at auction for a price above the money owed, the former property owner is owed the so-called “overbid proceeds,” which are typically held at the county level. But, counties typically send notifications about the funds to the foreclosed address, so many people remain unaware of the extra cash, according to Mary Pitman, author of “The Little Book of Missing Money.” These funds are differentthan other unclaimed funds in that the property owner’s claim in some counties only last a few years. Contact the county clerk to find out which local agency holds the funds.